Fuse construction



April 29, 1941. w. o. SCHULTZ FUSE CONSTRUCTION Filed Feb. 2'7, 1939 2 Sheets-Sheet 2 Rmm.

Patented Apr. 29, 1941 UNITED STATE FUSE CONSTRUCTION William 0. Schultz, South Milwaukee, Wis., assignor to Line Material Company, South Milwaukee, Wis, a corporation of Delaware Application February 27, 1939, Serial No. 258,708

27 Claims.

This invention relates to fuse constructions. Objects of this invention are to provide a novel form of fuse, preferably-a housed type of expulsion fuse, in which the fuse tube remains stationary after it has blown and the door remains closed, and in which the fuse tube is relieved of potential stress between the contacts after it has blown so that there is no danger of burning the fuse tube or the door even though the fuse tube may be left in an unfused condition for a material length of time.

Further objects are to provide a construction in which an indicator or semaphore is provided and is displayed when the fuse has blown, thereby giving an indication that the fuse has blown, and" to provide means for mechanically withdrawing the fuse link, such means acting in a direction substantially in line with the fuse tube at the initial portion of its stroke as distinguished from pulling the link around the end of the tube, whereby links of less flexibility may be used and whereby a positive extraction of any remaining portion of the fuse link is provided by mechanical means so that in addition to the expulsion action of the fuse tube there is a mechanical clearing of the fuse tube.

Further objects are to provide means for further interrupting the circuit in addition to that produced by the fusing of the fuse link, such means coming into operation only after the fuse link has melted and has been expelled or withdrawn from the fuse tube, such additional means operating although the fuse tube remains stationary.

Further objects are to provide a construction in which the mechanical means for withdrawing any remaining portion of .the fuse link and the auxiliary means for further interrupting the circuit, in addition to that provided by the melting of the fuse link, are supported from the door.

} in which the entire assembly of fuse tube, door andmechanical link extracting means and circuit interrupting means may be removed from the housing as a unit for refusing so that the device may be refused while it is completely detached from the remaining portion of the apparatus.

Further objects of this invention are to provide an automatically acting switch which is normally latched closed and is permanently biased towards open position, in which the latching means alone resists the contact pressure of the switch, and in which the fuse link controls the latching means, which latching means also acts as a fuse link extracting-means and additionally prevents the transmission of any stress tothe fuse link due to the contact pressure of the switch.

In greater detail, a further object of this invention is to provide an automatically acting switch preferably located adjacent the lower end of the fuse tube and controlled by the fuse link, the semaphore indicating means and the fuse extracting means being also controlled by the fuse link, the switch being held closed until the interruption of the circuit has been efi ected in the fuse tube and thereafter the switch moving to open position with a quick break and remain ing in open position, thus providing an additional point of interruption in the circuit and relieving the fuse tube of potential stresses.

Further objects are to provide a fuse construction in which the automatically operating switch separates any projecting portions of the apparatus or any remaining portion of the fuse link, after the .switch has operated, from electrical connection with any live contact of the fuse structure, thereby avoiding hazards. For example, in a construction in which a housing is provided and in which the semaphore or other indicating means is projected outwardly beyond the housing, such semaphore is electrically dead after the operation of the device.

An embodiment of the invention is shown in the accompanying drawings, in which:

Figure 1 is a vertical sectional view through the device, with parts broken away and in section showing the fuse in its normal position.

Figure 2 is a bottom view of the structure shown in Figure 1 showing the parts immediately adjacent the lower portion of the structure and omitting the parts above the lower portion of the structure for the sake of clearness.

Figure 3 is a fragmentary view of the lower portion of the device, such view corresponding to Figure-1 but showing the parts in the position they occupy after the fuse has blown.

Referring to the drawings, it will be seen that a housing I of porcelain or otherinsulating material has beenprovided and has upper and lower terminals or contacts 2 and 3 which are provided with conductor receiving means 5 and 6 for receiving conductors which may pass through suitable apertures, not shown, formed in the casing in the usual manner. The housing carries a pair of hook like hinge members I which detachably receive the trunnions l of a door 9 formed of suitable insulating material and provided with a manipulating eyelet portion ll, whereby the door may be opened or closed, the door rocking which the leader I8 of the fuse link passes. fuse link comprises the reduced fusible section the upper portion I6 and adapted to receive the head i1 of a fuse link therebetween. If desired, the cap it may be provided with a recessed portion I8 which receives the depressed portion l2 of the contact finger It to thereby lock the door closed. The spring finger ll presses downwardly on the flat portion of the cap I! and secures a good adequate electrical contact therebetween.

The fuse tube has an open lower end through The 26' which. may be connected between the flexible leader l9 and the section 2 l A combined indicating and fuse link extracting member is provided in the form-of a semaphore having a pair of segmental arms 26 which may if desired be brightly painted to increase their visibility when they are rocked downwardly into the position shown in Figure 3, thus indicating that the fuse has blown. These arms 20 are joined by a front web 21 beneath which the leader I! of the fuse link is passed, the lower end of the fuse tube being notched, if so desired, to form a guide for the fuse link iii. The segments 20 are also joined by a rear web 22 which carries the screw 23 that receives the clamping nut 24 for clamping the end of the leader I! of the fuse in place.

The web 22 is turned upwardly as shown in Figure 1 to provide a portion 25 which is cylindrical and whose center is the center of the pivot pin 26 for the semaphore. The pivot pin 26 is carried by a pair of spaced arms 21 which are formed integrally with the metal block 28 through which the fuse tube passes and to which the fuse tube is rigidly attached. The block 28 is provided with feet 29 which are secured to the door 9 as shown in Figure 1. The arms 21, it is to be noted from Figure l, are duplicates on opposite sides of the fuse tube and are generally of L shape. Their rear ends are lipturned and-are joined by a transverse web 30. The arms 20 of the semaphore are located outside of the arms 21 of the supporting member and are preferably outwardly flared, as shown in Figure 2, so as to clear the vertical portions of the arms 21.

A spring 3| is loosely coiled about the pin 26 and bears against the transverse web 22 of the semaphore and against the transverse web 36 of the arms 21. A switch is provided and comprises the upwardly projecting arm 32 which is integral with a pair of side arms 33. The side arms 33 are positioned between the stationary arms 21 of the support and are pivoted on a pivot pin 34 which passes through the supporting arms 21 and through the arms 33 of the switch. The switch is provided with any suitable contact portion as indicated at 35, preferably of the brush contact type. A spring 36 is loosely coiled about the pin II and bears at one end against the fuse tube It and at the other endagainst the lower portion of the arm 32 of the switch, thus permanently biasing the switch towards open position. If desired, sleeves, not shown, may be placed around the pins 26 and 34 to provide seats for the springs 31 and 36. Whether or not sleeves are used, the springs aesaooa are not allowed to bind upon their respective pins.

The arms 33 of the switch are provided with cylindrical cam faces 31 which, when the switch is in the position shown in Figure l, are concentric with the axis of the pin 26 so that although the switch is spring biased open, nevertheless the force tending to open the switch due to both its biasing action and the contact pressure against the stationary contact, is transmitted radially through the cam member 26, which also is concentric with the center of the pin 26, directly radially to the pin 26 and consequently there is no force transmitted by the arms 33 to the semaphore tending to rotate the semaphore.

It is to be noted that the fuse tube shields the fuse link from the switch.

The operation of the apparatus is as follows:

Upon rupture of the fuse link, the combined indicating and fuse link extracting means, namely, the semaphore, rocks to its exposed position as shown in Figure 3 and quickly withdraws any remaining portion of the fuse link, thus completely interrupting the circuit within the fuse tube. It executes a substantial portion of its motion prior to the time that the cam member start towards opening position that the switch receives from the pressure of its yielding con tact portion against the stationary contact. The final position of the parts is shown in Figure 3.

The fuse tube remains stationary during this entire operation and the circuit is interrupted first within the fuse tube and thereafter at another point, due to the opening of the switch. There is thus no potential stress imposed on the fuse tube itself when the switch is opened and consequently, though the device may remain unfused for a considerable length of time, there is no gradual damage to the fuse tube as it is com pletely relieved of potential stresses.

Additionally it is to be noted that the substantially direct downward pull on the fuse link causes the moving parts to acquire considerable velocity and accumulated energy before a change in the direction of pull on the fuse link is pronounced enough to cause appreciable friction between the leader and the side walls of the tube. The result is that even where a stiff leader is used, the momentum of the moving parts would overcome any reasonable friction and stiffness, even though a considerable portion of the leader was not destroyed when the fuse blew,

It is to be noted that after the fuse has blown and the device has operated, that any parts proiecting below the bottom of the casing are electrically dead as\the lower portion of the apparatus is electrically disconnected from the stationary lower contact, as shown very clearly in Figure 3, and there is, therefore, no hazard due to these projecting parts such as the semaphore and any remaining portion of the fuse link. This is especially important if the semaphore is made of conducting material, which is the form shown and described, though the invention In refusing the device, the lineman pulls the door open and unhooks it from the casing.

azsaeoe Thereafter he places a new fuse in position. He

rocks the switch to its closed position as shown in Figure 1, while the door is removed from the casing, and thereafter rocks the semaphore into its non-signalling position, also as shown in Figure 1, and clamps the leader of the fuse link by means of the thumb nut 24. Thereafter he hooks the door back into the hooks I of the casing and rocks the door closed.

It will be seen that a novel form of expulsion fuse has been provided in which an automatic switch is permanently biased towards open position but is under the control of the fuse link and is restrained from opening movement until after the fuse link has been ruptured and until after the circuit has been interrupted within the fuse tube.

It will be seen further that the device is of very simple construction and is easy and safe to handle and that it is a simple matter to refuse the device after the door has been removed.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim: 1

1. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts, a fuse link within said fuse tube, a normally closed switch permanently biased towards open position, and latch means controlled by said fuse link for normally restraining said switch against opening movement, said fuse link and said'switch being connected in series between said stationary contacts.

2., In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts, a fuse link within said fuse tube, a normally closed switch permanently biased towards open position, and latch means controlled by said fuse link for normally restraining said switch against open in movement, said fuse link and said switch being connected in series between said stationary contacts and said fuse tube remaining in position after blowing of said fuse link,

3. In a fuse construction, a fuse tube, a pair of stationary contacts, a normally closed switch permanently biased towards open position, and a fuse link within said fuse tube normally restraining said switch against opening movement, said switch having movement independently of any motion of said fuse tube.

4. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts, a normally closed switch permanently biased towards open position, and a fuse link within said fuse tube normally restraining said switch against opening movement, said switch having movement independently of any motion of said fuse tube, said fuse tube remaining in position after the blowing of said fuse link.

5. In a fuse construction, a stationary contact, a switch normally engaging said stationary contact .and permanently biased towards open position, and a fuse link in series with said switch and restraining said switch against opening movement, said switch being relased upon rupture of said fuse link.

6. In a fuse construction, a stationary contact, a switch normally engaging said stationary contact and permanently biased towards open position, and a 'fuse link in series with said switch and restraining said switch against opening movement, said switch being released upon rupture of said fuse link, said fuse link having a fusible section remote from said switch.

7. In a fuse construction, a. stationary contact, a switch normally engaging said stationary contact and permanently biased towards open position, a fuse link in series with said switch and restraining said switch against opening movement, means shielding said fuse link from said switch, said switch being released upon rupture of said fuse link.

8; In a fuse construction, a stationary contact, a switch normally engaging said stationary contact and permanently biased towards open position, a fuse link in series with said switch and restraining said switch against opening movement, means shielding said fuse link from said switch, said switch being released upon rupture of said fuse link, said fuse link having a fusible section remote from said switch.

9. In a fuse construction, a stationary contact, a switch normally engaging said stationary contact and permanently biased towards open position, a latch normally restraining said switch against opening movement, and a fuse link in series with said switch and normally restraining said latch, said latch being released upon rupture of said fuse link, whereby said switch will move to open position,

10. In a fuse construction, a stationary contact, a switch normally engaging said stationary contact and permanently biased towards open position, a latchnormally restraining said switch against opening movement, a fuse link in series with said switch and normally restraining said latch, and means shielding said fuse link from said switch, said latch being released upon rupture of said fuse link, whereby said switch will move to open position.

11. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts, said fuse tube having a contact connected with one of said stationary contacts, a switch normally engaging the other of said stationary contacts and permanently biased towards open position, and

a fuse link within said fuse tube restraining said switch from movement to open position, said fuse link and switch being in series between said stationary contacts.

a 12. In a fuse construction, a relatively stationary fuse tubeya pair of stationary contacts, said fuse tube having a contact connected with one of said stationary contacts, a switch normally engaging the other of said stationary contacts and permanently biased towards open position, latch means normally restraining said switch against opening movement, and a fuse link within said fuse tube normally restraining said latch means against releasing movement, said fuse link and said switch being in series between said stationary contacts.

13. In a fuse construction, a relativelystationary fuse tube, a pair of stationary contacts, said fuse tube having 'a contact connected with one of said stationary contacts, a switch normally engaging the other of said stationary contacts and permanently biased towards open position, latch means biased towards releasing movement and normally restraining said switch against ;opening movement, and a fuse link within said fuse tube normally restraining said latch means against releasing movement, said fuse link and said switch being in series between said station- 'ary contacts.

14. In a fuse construction, a relatively stationary fuse tube, a pair of the stationary contacts,

said fuse tube having a contact adjacent one end connected to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the other of said-stationary contacts and permanently biased towards open position away from such other stationary contact, and a fuse link within said fuse tube connected in series with said switch between said stationary contacts and normally restraining said switch against opening movement, said switch when in open position isolating said other end of said fuse tube from said other stationary contact.

15. In a fuse construction, a relatively stationary fusetube, a pair of stationary contacts, said fuse tube having a contact adjacent one end connected to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the other of said stationary contacts and permanently biased towards open position away from such other stationary contact, a latch normally restraining said switch against opening movement, and a fuse link connected in series with said switch between said stationary contacts and restraining said latch ggalnst releasing movement, said switch when in open position isolating said other, end of said (use tube from said other stationary contact. 16. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts, said fuse tube having a contact adjacent one end connected to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the other of said stationary contacts and permanently biased towards open position away from such other stationary contact, a latch biased towards releasing movement normally restraining said switch against opening movement, and a fuse link connected in series with said switch between said stationary contacts and restraining said latch against releasing movement, said switch when in open position isolating said other end of said fuse tube from said other stationary contact.

1'7. In a fuse construction, a housing having an upper and a lower stationary contact, a fuse tube mounted within said housing and pivoted independently of either of said contacts, said fuse tube having an upper contact connected to the upper stationary contact, a switch adjacent the lower end of said fuse tube normally engaging the lower stationary contact, said switch being biased towards movement away from said lower stationary contact, and a fuse link within said fuse tube connected in series with said switch between said stationary contacts and normally restraining said switch against opening movement, said switch when in open position isolating the lower end of said fuse tube from said lower stationary contact.

18. In a fuse construction, a housing having an upper and a lower stationary contact, a fuse tube within said housing having an upper contact engaging said upper stationary contact, a switch adjacent the lower end of said fuse tube normally engaging the lower of said stationary contacts. and permanently biased towards open position away from said lower stationary contact, signalling means adjacent the lower end of said fuse tube normally housed within said housing and biased towards motion to an exposed position outside of said housing, said switch being controlled by said signalling means. and a fuse link within said fuse tube connected in series with said switch between said upper and lower stationary contacts and restraining said signalling means and said switch from movement, said switch when in open position isolating the lower end of said fuse tube from said lower stationary contact.

19. In a fuse construction, a housing having an upper and a lower stationary contact, a fuse tube within said housing having an upper contact engaging said upper stationary contact, a switch adjacent the lower end of said fuse tube normally engaging the lower of said stationary contacts and permanently biased towards open position away from said lower station contact, signalling means adjacent the lower end of said fuse tube "normally housed within said housing and biased towards motion to'an exposed position outside of said housing, said signalling means normally latching said switch against opening movement and said switch having movement independently of said signalling means when released from said signalling means, and a fuse link within said fuse tube connected in series with said switch between said upper and lower stationary contacts and normally restraining said signalling means from outward motion, said switch when in open position isolating the lower end of said fuse tube from said lower stationary contact.

20. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts. said fuse tube having a contact adjacent one end connected to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the other of said stationary contacts and permanently biased towards open position away from such other stationary 'contact, signalling means adapted to occupy a signalling position and a non-signalling position, and a fuse link within said fuse tube connected in series with said switch between said stationary contacts and normally restraining said signalling means against movement from non-signalling to signalling position, said switch being controlled by said signalling means, said switch when in open position isolating said other end of said fuse tube from said other stationary contact.

21. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts. said fuse tube having a contact adjacent one end connected to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the other of said stationary contacts and permanently biased towards open position away from such other stationary contact, a combined latch and fuse link extracting means normally/restraining said switch against opening movement and biased towards fuse link extracting movement, and a fuse link within said fuse tube connected in series with said switch between said stationary contacts and restraining said combined latch and fuse link extracting means from movement, said switch when in open position isolating said other end of said fuse from said other stationary contact.

22. In a fuse construction, a relatively stationary fuse tube, a pair .of stationary contacts, said fuse tube having a contact adjacent one end connected'to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the other of said stationary contacts and permanently biased towards open position away from such other stationary contact, a latch for latching said switch against open ing movement, and a fuse link within said fuse tube connected 'in series with said switch between said stationary contacts and restraining said latch against releasing movement, the contact pressure of said switch being borne solely by said latch, whereby said fuse link is not stressed by the contact pressure of said switch.

23. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts, a fuse link within said fuse tube, a normally closed switch permanently biased towards open position, and latch means controlled by said fuse link for normally restraining said switch against opening movement, said fuse link and said switch being connected in series between said stationary contacts, said latch means holding said switch closed until the circuit is interrupted within said fuse tube.

24. In a fuse construction, a fuse tube, a fuse link within said fuse tube, a pair of stationary contacts, said fuse tube having a contact adjacent one end connected. to one of said stationary contacts, a switch adjacent the other end of said fuse tube normally engaging the'other. of said stationary contacts and permanently biased towards open position away from said stationary contact, said switch having motion independently of said fuse tube, and mechanism including a latch and a fuse link extracting means, said latch latching said switch against opening movement until said fuse link extracting means has moved any remaining portion of said fuse link sufficiently to interrupt the circuit within said fuse tube, said switch and said fuse link being connected in series between said stationary contacts, and said latch and fuse link extracting means being normally restrained by said fuse link.

25. In a fuse construction, a housing having an upper and a lower stationary contact, a fuse tube within said housing having an upper .contact engaging said upper stationary contact, a switch adjacent the lower end of said fuse tube normally engaging the lower of said stationary contacts and permanently biased towards open position. away from said lower stationary contact, signalling means adjacent the lower end of said fuse tube normally housed within said housing and biased towards motion to an exposed position outside of said housing, said switch being controlled by said signalling means, and a fuse link within said fuse tube connected in series with said switch between said upper and lower stationary contacts and restraining said signalling means and said switch from movement, said switch when in open position electrically isolating said signalling means from any live portion of said fuse construction.

26. In a fuse construction, a relatively stationary fuse tube, a, pair of stationary contacts, said fuse tube havinga contact adjacent one end con nected to one of said stationary contacts, a

switch adjacent the other end of said fuse tube normally engaging the other of said stationary contacts and permanently biased towards open position away from such other stationary contact, a combined latch and fuse link extracting means normally restraining said switch against opening movement and biased towards fuse link extracting movement, and a fuse link within said fuse tube connected in series with said switch between said stationary contacts and restraining said combined latch and fuse link extracting means from movement, said switch when in open position electrically isolating said combined latch and fuse link extracting means from any live portion of said fuse construction.

27. In a fuse construction, a relatively stationary fuse tube, a pair of stationary contacts,,a fuse link within said fuse tube, a normally closed switch permanently biased towards open position, and mechanism including fuse link extracting means and latch means, said mechanism being controlled by said fuse link and normally restraining said switch against opening movement, said fuse link and said switch being connected in series between said stationary contacts and said fuse link extracting means initially withdrawing any remaining portion of said fuse link substantially in line with said fuse tube.

WILLIAM O.- SCHULTZ. 

